Fluid control element

ABSTRACT

A fluid control element comprises a housing in which two control chambers are formed, which are isolated from each other and comprise a working port each as well as two pressure ports. Two of these ports are provided with a sealing seat each. The fluid control element further comprises a switching element movably mounted in said housing and comprising a sealing part in each control chamber. The sealing part cooperates with the sealing seats such that these are opened or closed. The fluid control element further comprises an actuating member for the switching element, the actuating member being able to bring the switching element into three positions.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,765,370 shows a fluid control element comprising ahousing in which two control chambers are formed, which are eachisolated from each other and comprise a working port each as well as twopressure ports, two of the ports being provided with a sealing seateach. The fluid control element further comprises a switching elementmovably mounted in the housing and comprising a sealing part in eachcontrol chamber, the sealing part cooperating with the sealing seatssuch that these are opened or closed, and still further comprises anactuating member for the switching element. This fluid control elementrepresents a 4/2-way valve for actuating hydraulic actuator cylinders,for example. When actuating, for example, a double-acting hydrauliccylinder, the working port of the one control chamber is connected to aworking port of the hydraulic cylinder and the working port of the othercontrol chamber is connected to the other working chamber of thehydraulic cylinder. In a first position of the switching element, theresting position, the one working chamber of the hydraulic cylinder ispressurized so that a movement occurs in a first direction, whilst in anactivated position of the switching element into which the switchingelement is moved by an electric magnet, the other working chamber of thehydraulic piston is pressurized so that a movement occurs in theopposite direction.

It is often required, however, in addition to a movement of thehydraulic piston in a first and a second direction that the hydraulicpiston, for example, is maintained fixed in a position or is freelymovable. For this purpose 4/3-way valves are needed as described withreference to FIG. 13. Illustrated schematically in FIG. 13 is ahydraulic piston 1 disposed between two working chambers 2, 3. Theworking chamber 2 is connected to a working port A of a 4/3-way controlelement illustrated schematically and identified by reference numeral10, and the working chamber 3 is connected to a working port B.Furthermore, two pressure ports P, R are provided, port P providing apressurized fluid and port R forming a return flow conduit.

The control element shown as example 1 permits three operatingconditions. In the left-hand switching position the hydraulic piston 1is biased so as to move to the right. In the middle switching positionthe hydraulic piston 1 is blocked. In the left-hand switching positionthe hydraulic piston 1 is biased so as to move to the left.

The examples 2 and 3 likewise make possible three switching positions,the left-hand and the right-hand switching positions in each casecorresponding to the right-hand and left-hand switching positions of thefirst example. The middle switching position in example 2 results in thehydraulic piston 1 being freely movable and the middle switchingposition of example 3 results in the hydraulic piston 1 being blocked bythe pressure furnished by the pressure port P.

Hitherto, achieving such switching functions necessitated the use ofpiloted slide valves.

The object of the invention consists in providing a simple,direct-acting control element having a 4/3 operational mode to thusreduce the expense in terms of technical equipment in actuating acylinder and to permit a more direct and faster operation of actuatorcylinders and actuators, respectively.

BRIEF DESCRIPTION OF THE INVENTION

To achieve this object, a fluid control element is provided whichcomprises a housing in which two control chambers are formed, which areisolated from each other and comprise a working port each as well as twopressure ports. Two of these ports are provided with a sealing seateach. The fluid control element further comprises a switching elementmovably mounted in the housing and comprising a sealing part in eachcontrol chamber. The sealing part cooperates with the sealing seats suchthat these are opened or closed. The fluid control element furthercomprises an actuating member for the switching element, the actuatingmember being able to bring the switching element into three positions.In this way the desired three switching positions are achievable with acontrol element having two control chambers without additional slidevalves being necessary. Such an actuating member with which theswitching element is may be brought into three positions is, for examplea solenoid drive having a polarized drive element, the permanent magnetof which in the non-energized condition of its solenoid holds theswitching element in a middle position, which also represents theresting position, and in the energized condition shifts the switchingelement into the one or the other direction depending on the directionof current flow.

In accordance with one preferred embodiment of the invention it isprovided for that the sealing seats of one control chamber are disposedopposite each other on the one and the other side of the control chamberand that the sealing part arranged in this control chamber is configuredwith two opposing tongues disposed between the sealing seats andconfigured so as to be elastically resilient, and in the restingposition are spaced away from each other such that they maysimultaneously close the two sealing seats. In this embodiment all portsin the middle or resting position are closed. By moving the switchingelement, starting from the resting position, into the one or the otherdirection the desired ports may be selectively opened.

As an alternative it may be provided for that the sealing seats of onecontrol chamber are disposed opposite each other on the one and theother side of the control chamber and the sealing part arranged in thiscontrol chamber is in contact with either the one or the other sealingseat. In this embodiment one sealing seat of each control chamber isclosed in the resting position. As soon as the switching element isactuated in any direction, one of the sealing parts is lifted from thecorresponding sealing seat and pressed against the opposite sealing seatwhilst the other sealing part remains in contact at the correspondingsealing seat with no change in the switching condition in this controlchamber. Depending on how the various ports are put in circuit, avariety of different switching conditions results.

In this alternative the sealing parts arranged in the two controlchambers extend in the same plane or in different planes. In the restingposition one of the sealing parts is then in contact with the sealingseat disposed on one side of the corresponding control chamber whilstthe other sealing part is in contact with the other sealing seatarranged at the other side of the other control chamber. When thesealing parts are arranged in the same plane, the actuating travelneeded for making the changeover is achieved by differing the spacing ofthe sealing seats away from the plane of the sealing parts in theresting position, whereas when the sealing parts are arranged indifferent planes the necessary actuating travel is achieved by differentspacings assumed by the sealing seat from the sealing parts being in theresting position.

In accordance with a further embodiment it may be provided for that thesealing seats of one control chamber are arranged mutually staggered onthe one and on the other side of the control chamber, and that thesealing part arranged in this control chamber is configured with twotongues arranged side by side, each of which being assigned to one ofthe sealing seats and configured so as to be springy and elastic. Theeffect of this configuration is basically the same as that describedabove having the two tongues opposite each other, except that here alarger number of switching conditions is possible. If required, in oneof the control chambers the configuration as described above includingopposite sealing seats and opposite tongues may be provided, whilst inthe other control chamber the configuration having staggered sealingseats and tongues lying side by side may be employed.

It is preferably provided for, however, that in both control chambersthe sealing seats of one control chamber are arranged mutually staggeredon the one and the other side of the corresponding control chamber, amaximum number of switching conditions being possible in this case.

In this embodiment it may be either provided for that the tongues of thesealing parts of the switching element arranged in the two controlchambers extend in the same plane. Technically the same effect isachievable by providing the two tongues, arranged in one chamber, so asto be mutually staggered. In cooperation with a suitable arrangement ofthe sealing seats relative to the arrangement of the tongues in theresting position, a variety of conditions is possible, i.e. the sealingseats in the two control chambers either being arranged such that in theresting position the tongues of the sealing parts are in contact withall sealing seats in the two control chambers, or as an alternative thesealing seats in the two control chambers are arranged such that in theresting position the tongues of the sealing parts are in contact withall sealing seats of a sole control chamber and with no sealing seat ofthe other control chamber. Finally, it is possible that the sealingseats are arranged in the two control chambers such that in the restingposition the tongues of the sealing parts are each in contact with onesealing seat in each control chamber. Depending on the configurationselected in each case a wealth of different switching conditions isachieved with which any desired mode of actuating an actuator, forexample a hydraulic actuating cylinder, is achievable.

Advantageous aspects of the invention read from the sub-claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to variousembodiments illustrated in the attached drawings in which

FIG. 1 is a schematic illustration of part of a housing of a controlelement in accordance with the invention, comprising the control chamberand the sealing part arranged therein,

FIG. 2 is a schematic section view of a control element in accordancewith the invention;

FIG. 3 is a schematic cross-section through the two control chambers ofa control element according to a first embodiment of the invention;

FIG. 4 is a broken view in perspective of a sealing part employed in thecontrol element as shown in FIG. 3;

FIG. 5 is a schematic plan view of a switching element as may be used ina control element in accordance with a second embodiment of theinvention;

FIG. 6 shows in a schematic cross-section through the control chamber acontrol element according to the second embodiment of the invention;

FIG. 7 is a view, corresponding to that as shown in FIG. 6, of a controlelement in accordance with one variant of the second embodiment of theinvention;

FIG. 8 is a schematic cross-section through the control chamber of acontrol element in accordance with a third embodiment of the invention;

FIG. 9 is a schematic plan view of a switching element as may be used ina control element according to FIG. 8;

FIGS. 10a, 10 b, 10 c, 10 d, and 10 e illustrate various designs of thecontrol element in accordance with the third embodiment;

FIGS. 11a, 11 b, 11 c, 11 d, and 11 e illustrate various designs of avariant of the third embodiment;

FIG. 12 is a schematic view of an actuating member as may be used withthe control elements in accordance with the invention; and

FIG. 13 is a schematic illustration of an actuator including variouscontrol elements.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, the configuration of the controlelements in accordance with the invention will now be described ingeneral. The control element 10 comprises a housing 12 in which twocontrol chambers 20, 30 are configured so as to lie side by side andisolated from each other (only one of the chambers can be seen in FIG.1). Opening into each control chamber is a working port and two pressureports, the working port being identified by A and B, respectively, andthe pressure ports by P and R, respectively. Two of the ports in eachcontrol chamber 20 and 30, respectively, are provided with a sealingseat 21, 22 and 31, 32, respectively. Cooperating with the sealing seats21, 22 and 31, 32 is a switching element identified in general by thereference numeral 14. The switching element 14 is movable from a restingposition into a first and a second position by acting on an actuatorprotuberance 15. In all, three positions of the switching element 14 arethus possible. For actuating the switching element 14 an actuatingmember 16 is provided (see also FIG. 12) configured, for example, as asolenoid drive having a polarized drive element, the permanent magnet ofwhich in the non-energized condition of a solenoid causes a middleposition of the actuator protuberance 15 and in the energized conditionshifts the actuating arm in the direction of either arrow 1 or arrow 2,depending on the direction of the current.

Referring now to FIG. 12 there are illustrated the two positions 1 and 2of a magnet 17 applied to the actuator protuberance 15. The solenoid ofthe actuating member is identified by the reference numeral 18 and theswitchable voltage source is identified in FIG. 12 by the referencenumeral 19.

The basic configuration of the switching element 14 consisting of a core11 and an elastomer 13 surrounding the latter, as well as the mountingarrangement of the switching element in the housing 12 is known inprinciple from U.S. Pat. No. 5,711,346 incorporated herein by reference.

Referring now to FIGS. 3 and 4 there is illustrated a control element aswill now be described in accordance with a first embodiment of theinvention. The switching element 14 protrudes into each control chamber20, 30 with a sealing part 24 and 34, respectively. The two sealingparts 24, 34 are fixedly connected to the actuator protuberance 15 andare moved simultaneously with the actuator protuberance. At the endfreely protruding into the corresponding control chamber each sealingpart 24, 34 is provided with two tongues 26, 28 and 36, 38,respectively. The two tongues 26, 28 and 36, 38, respectively, areconfigured so as to be elastically resilient and opposite each other. Asevident from FIG. 4 one of the tongues may be configured by a crank ofthe corresponding sealing part whilst the opposite tongue is formed byan additional part cranked mirror inverted and connected to the sealingpart, for example, by spot welding. Of course, provided around each ofthe tongues 26, 28 and 36, 38, respectively, is the elastomer layer 13known as such.

The sealing seats 21, 22 and 31, 32, respectively, which are arranged inthe control chambers 20, 30 are configured so as to lie opposite eachother (see FIG. 3). Although this is not necessarily the case, the portsassigned to the sealing seats 21, 22 and 31, 32, respectively, have thesame middle axis, i.e. the corresponding sealing seats are disposedcoaxially to each other. Opening into each control chamber on one sideof the sealing seats is the remaining port. In the configuration asshown in FIG. 3 the ports are put in circuit such that the sealing seatsare assigned to the two pressure ports P, R whilst the working port Aand B, respectively, opens into the side.

The spacing of the two sealing seats 21, 22 and 31, 32 assigned to eachother is selected such that in the resting position, i.e. with theactuator protuberance 15 not actuated, the two tongues 26, 28 and 36,38, respectively, close the corresponding sealing seats. This is evidentfrom FIG. 3. In this position all fluid ports are closed. When, startingfrom this position, the actuating protuberance is acted upon, thesealing parts 24, 34 are moved either upwards, resulting in the port Rof the control chamber 20 and the port P of the control chamber 30 beingconnected to the working ports A, B, or downwards, resulting in thepressure ports R of the control chamber 20 and P of control chamber 30being connected to the working ports A, B. It is in this way that a4/3-way control element is produced.

By differently putting the various ports of the illustrated controlelement in circuit, other switching conditions are possible, as willreadily be appreciated.

Referring now to FIGS. 5 and 6 there is described a second embodiment ofthe control element in accordance with the invention. The switchingelement 14 comprises two sealing parts 24, 34 arranged side by side andin the same plane (see more particularly FIG. 6). The sealing seats 21,22 and 32, 32, respectively, which are arranged in the control chambers20, 30 protrude into the control chambers differingly far. As evidentfrom FIG. 6 the sealing seat 21 arranged on the upper side of thecontrol chamber 20 protrudes so far into the control chamber that it isin contact with the sealing part 24 located in the starting position. Ina similar way the sealing seat 32 arranged on the underside of thecontrol chamber 30 protrudes so far into the control chamber that it isin contact with the sealing part 24 located in the resting position. Thesealing seat 22 arranged on the underside of the control chamber 20 aswell as the sealing seat 32 arranged on the underside of the controlchamber 30 are arranged spaced away from the sealing part 24 and 34,respectively, located in the resting position.

Referring now to the resting position of the sealing parts 24, 34 asshown in FIG. 6 the switching element can be made to assume twopositions. In a first position in which the two sealing parts 24, 34 arebiased so as to move upwards there is no further change in the positionof the sealing part 24 since it is already in contact with the sealingseat 21 and is elastically deformed, whereas the sealing part 34 islifted from the sealing seat 32 and pressed against the sealing seat 31.In this position the pressure port P is thus connected to the workingport B of the control chamber 30 whilst as regards the control chamber20 no change in the switching condition occurs. When, however, thesealing parts 24, 34 are biased so as to move downwards out of theresting position there is no change in the switching condition asregards the control chamber 30 whilst the sealing part 24 is lifted fromthe sealing seat 21 and pressed against the sealing seat 22. Now, thepressure port identified P in this case is connected to the working portA of the control chamber 20.

Referring now to FIG. 7 there is illustrated a variant of the secondembodiment as shown in FIGS. 5 and 6. The difference in this case beingthat, now, the sealing seats 21, 31 arranged on the upper side of thecontrol chambers 20, 30 as well as the sealing seats 22, 32 arranged onthe underside of the chambers are each located at the same level.Furthermore the sealing parts 24, 34 are no longer arranged in the sameplane, but mutually staggered.

The effect is similar to that as explained for the second embodiment.When starting from the resting position as shown in FIG. 7 the sealingparts 24, 34 are biased so as to move upwards there is no change in theswitching condition as regards control chamber 20 whilst the sealingpart 34 in the control chamber 30 is lifted from the sealing seat 32 andpressed against the sealing seat 31, whereas when the sealing parts 24,34 are biased so as to move downwards there is no change in theswitching condition as regards control chamber 30 whilst the sealingpart 24 of the control chamber 20 is lifted from the sealing seat 21 andpressed against the sealing seat 22.

Both in the second embodiment as shown in FIGS. 5 and 6 and in thevariant of the second embodiment as evident from FIG. 7, differentswitching conditions may be achieved by suitable swapping of putting theports in circuit.

Referring now to FIGS. 8 and 9 t here is described a third embodiment ofa control element in accordance with the invention. In this embodimentthe sealing seats arranged in the control chambers 20, 30 are no longerconfigured coaxially opposite each other, but mutually staggered asevident from FIG. 8. In this arrangement the sealing seats 21, 31arranged on the upper side of the control chambers 20, 30 protrude intothe control chambers up to the same level and also the sealing seats 22,32 arranged on the underside of the control chambers 20, 30 are eachlocated at the same level.

The sealing part of the switching element 14 protruding into the controlchamber 20 and 30, respectively, consists for each control chamber oftwo parallel tongues arranged side by side. Thus, two tongues 26, 28protrude into the control chamber 20 and two tongues 36, 38 protrudeinto the control chamber 30. All tongues 26, 28, 36, 38 extend in thesame plane in the resting position. As evident from FIG. 8 the spacingof the level defined by the sealing seats 21, 31 from the level definedby the sealing seats 22, 32 is dimensioned such that all tongues are incontact with their assigned sealing seats in the resting position of theswitching element 14, closing them off. In the resting position as shownin FIG. 8 all ports are thus blocked.

When starting from the resting position as shown in FIG. 8 the tongues26, 28, 36, 38 are biased so as to move upwards, there is no change inthe condition as regards the tongues 26, 36 since these tongues reactmerely elastically and continue to remain in contact with thecorresponding sealing seats, whereas the tongues 28, 38 are lifted fromtheir assigned sealing seats 22, 32 and the working port A of chamber 20is connected to the pressure port R, whilst the working port B ofcontrol chamber 30 is connected to the pressure port P.

Referring now to FIG. 10, in the illustrations a) to e) there are shownvarious control elements in accordance with a third embodiment eachachieving a different switching condition by a change in the spacing ofthe sealing seats from the corresponding tongues in the resting positionand by a different putting in circuit of the various ports. Theresulting switching conditions are evident from the illustrations andthe likewise indicated switching symbols so that there is no need todetail them.

Referring now to FIG. 11, in the illustrations a) to e) there are shownvarious control elements in accordance with a variant of the thirdembodiment on the basis of the gist as known from FIG. 7 showing thatthe tongues of the switching element are mutually staggered. In thisarrangement and in conjunction with differingly putting the ports incircuit and with different spacings between the sealing seats and thetongues in the resting position, the same switching conditions areachievable as already shown in the illustrations a) to e) as evidentfrom FIG. 10.

What is claimed is:
 1. A fluid control element, comprising a housing inwhich two control chambers are formed, which are isolated from eachother and comprise a working port each as well as two pressure ports,two of said ports being provided with a sealing seat each, a switchingelement movably mounted in said housing and comprising a sealing part ineach control chamber, said sealing part cooperating with said sealingseats such that these are opened or closed and comprising an actuatingmember for said switching element, said actuating member being able tobring said switching element into three positions, said sealing seats ofat least one of said control chambers being disposed opposite each otheron the one and the other side of said control chamber and wherein saidscaling part arranged in said one of said control chambers is configuredwith two opposing tongues disposed between said sealing scats andconfigured so as to be elastically resilient, whereby, in a restingposition wherein said actuating member is not actuated, said opposingtongues are spaced away from each other such that they maysimultaneously close said two sealing seats.